let fp = require('lodash/fp')
const cars = [
  {name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true},
  {name: 'Spyker Cer Zagato', horsepower: 650, dollar_value: 648000, in_stock: false},
  {name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false},
  {name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false},
  {name: 'Aston Martin One-77', horsepower: 750, dollar_value: 185000, in_stock: true},
  {name: 'Pagani Huayra', horsepower: 700, dollar_value: 130000, in_stock: false},
]
// 练习 1 
let lastProp = fp.flowRight(fp.prop('in_stock'), fp.last)
console.log(lastProp(cars))

// 练习 2 
let firstName = fp.flowRight(fp.prop('name'), fp.first)
console.log(firstName(cars))

// 练习 3 
let _average = function(xs) {
  return fp.reduce(fp.add, 0, xs) / xs.length
}
const averageDollarValue = fp.flowRight(_average, fp.map(car => car.dollar_value))
console.log(averageDollarValue(cars))

// 练习 4 
let _underscore = fp.replace(/\W+/g, '_')
let sanitizeNames = fp.flowRight(fp.map(_underscore), fp.map(car => car.name))
console.log(sanitizeNames(cars))
